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International audience; Doping of transition metals within a semiconductor quantum dot (QD) has a high impact on the optical and magnetic properties of the QD. In this study, we report the synthesis of Mn 2+-doped Ag−In−Ga−Zn−S (Mn:AIGZS) QDs via thermolysis of a dithiocarbamate complex of Ag + , In 3+ , Ga 3+ , and Zn 2+ and of Mn(stearate) 2 in oleylamine. The influence of the Mn 2+ loading on the photoluminescence (PL) and magnetic properties of the dots are investigated. Mn:AIGZS QDs exhibit a diameter of ca. 2 nm, a high PL quantum yield (up to 41.3% for a 2.5% doping in Mn 2+), and robust photo-and colloidal stabilities. The optical properties of Mn:AIGZS QDs are preserved upon transfer into water using the glutathione tetramethylammonium ligand. At the same time, Mn:AIGZS QDs exhibit high relaxivity (r 1 = 0.15 mM −1 s −1 and r 2 = 0.57 mM −1 s −1 at 298 K and 2.34 T), which shows their potential applicability for bimodal PL/magnetic resonance imaging (MRI) probes.

We present results on the photothermal (PT) and heat conductive properties of nanogranular silicon (Si) films synthesized by evaporation of colloidal droplets (drop-casting) of 100 ± 50 nm-sized crystalline Si nanoparticles (NP) deposited on glass substrates. Simulations of the absorbed light intensity and photo-induced temperature distribution across the Si NP films were carried out by using the Finite difference time domain (FDTD) and finite element mesh (FEM) modeling and the obtained data were compared with the local temperatures measured by micro-Raman spectroscopy and then was used for determining the heat conductivities k in the films of various thicknesses. The cubic-to-hexagonal phase transition in Si NP films caused by laser-induced heating was found to be heavily influenced by the film thickness and heat-conductive properties of glass substrate, on which the films were deposited. The k values in drop-casted Si nanogranular films were found to be in the range of lowest k of other types of nanostructurely voided Si films due to enhanced phonon scattering across inherently voided topology, weak NP-NP and NP-substrate interface bonding within nanogranular Si films.

International audience; A single source molecular precursor synthesis of new quinary Ag-In-Ga-Zn-S (AIGZS) QDs is presented. Dithiocarbamate complexes with varied Ag/In/Ga/Zn ratios were prepared from AgNO3, In(NO3)3, Ga(NO3)3 and Zn(diethyldithiocarbamate)2. The thermal decomposition of these complexes at 220°C in oleylamine produces AIGZS QDs emitting from the visible to the near-infrared region and with photoluminescence quantum yields (PL QYs) up to 48.3%. For AIGZS QDs prepared with a (Ag + In + Ga)/Zn molar ratio of 1, intragap states likely involving Ag + ions are responsible of the PL emission and the PL lifetime could reach 278 ns. A marked increase of the PL lifetime (up to 915 ns) was observed when decreasing the (Ag + In + Ga)/Zn molar ratio to 0.5. The optical properties of AIGZS QDs could be maintained after transfer in aqueous solution. AIGZS should be of high potential for various applications due to their PL emission tunability and high PL QYs.

All-solid-state batteries were fabricated by assembling a layer of self-organized TiO2 nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO4 as a cathode. The synthesis of self-organized TiO2 NTs from Ti-6Al-4V alloy was carried out via one-step electrochemical anodization in a fluoride ethylene glycol containing electrolytes. The electrodeposition of the polymer electrolyte onto anatase TiO2 NTs was performed by cyclic voltammetry. The anodized Ti-6Al-4V alloys were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the anodized Ti-6Al-4V alloys were investigated by cyclic voltammetry and chronopotentiometry techniques. The full-cell shows a high first-cycle Coulombic efficiency of 96.8% with a capacity retention of 97.4% after 50 cycles and delivers a stable discharge capacity of 63 μAh cm−2 μm−1 (119 mAh g−1) at a kinetic rate of C/10.

International audience; Self-organized Titanium dioxide (TiO2) nanotubes grown on Ti grid acting as anode for Li-ion microbatteries were prepared via an electrochemical anodization. By tuning the anodization time, the morphology and length of the nanotubes were investigated by scanning electron microscope. When the anodization time reached 1.5 h, the TiO2nts/Ti grid anode showed a well-defined nanotubes, which are stable, well-adherent ~90 nm with a length of 1.9 ± 0.1 μm. Due to their high surface utilization, surface area, and material loading per unit area, TiO2nts/Ti grid anode using polymer electrolyte exhibited a high areal capacity of 376 μAh cm−2 at C/10 rate and a stable discharge plateau at 1.8 V without using a polymer binder and conductive additive. The storage capacity of the TiO2nts/Ti grid after 10 cycles is 15 times higher compared to previous reports using planar Ti foils.

Mn-Doped quantum dots (QDs) are of high interest for numerous applications like solar cells, optoelectronics, optosensing, or bioimaging. Here, we report the preparation of quaternary (AgInS2)x(MnS)y(ZnS)1−x−y QDs, thereafter noted Mn : AIZS via a thermally induced decomposition of Ag, In, Zn and Mn precursors in the presence of oleylamine and dodecanethiol. The Mn : AIZS QDs have an average diameter of 3.5 nm and their XRD patterns can be indexed with the orthorhombic phase of AgInS2. The incorporation of Mn2+ ions in the AIZS crystal lattice results in a red-shift of the photoluminescence (PL) emission maximum depending on the Mn2+ content. The PL quantum yields decrease upon loading with Mn2+ but remained high (53–31%) until 50% theoretical loading in Mn2+. Steady state, PL excitation and time-resolved PL measurements suggest that Mn2+-dependent trap states are involved in the PL emission. Mn : AIZS QDs exhibit also magnetic properties. In addition, Mn : AIZS QDs can easily be transferred to the aqueous phase using the PMAO amphiphilic polymer without alteration of their optical properties (PL quantum yield up to 51%), revealing their high potential for biological applications.

Hydrogen generation rate is one of the most important parameters which must be considered for the development of engineering solutions in the field of hydrogen energy applications. In this paper, the kinetics of hydrogen generation from oxidation of hydrogenated porous silicon nanopowders in water are analyzed in detail. The splitting of the Si-H bonds of the nanopowders and water molecules during the oxidation reaction results in powerful hydrogen generation. The described technology is shown to be perfectly tunable and allows us to manage the kinetics by: (i) varying size distribution and porosity of silicon nanoparticles, (ii) chemical composition of oxidizing solutions, (iii) ambient temperature. In particular, hydrogen release below 0 &deg, C is one of the significant advantages of such a technological way of performing hydrogen generation.

International audience; We report the electrodeposition of polymer electrolyte (PMMA-PEG) in porous lithium nickel manganese oxide (LiNi0.5Mn1.5O4) cathode layer by cyclic voltammetry. The cathode-electrolyte interface of the polymer-coated LNMO electrode has been characterized by scanning electron microscopy and electrochemical techniques. Electrochemical measurements consisting of galvanostatic cycling tests and electrochemical impedance spectroscopy revealed a significant improvement of the capacity values and the increase of the operating voltage. These effects are attributed to the total filling of pores by the electrodeposited polymer that contributes to improve the reversible insertion of Li+. A complete all-solid-state microbattery consisting of electropolymerized LNMO as the cathode, a thin polymer layer as the electrolyte, and TiO2 nanotubes as the anode has been successfully fabricated and tested.

International audience; This work describes the performance of poly(ethylene-co-vinyl acetate) (EVA) copolymer and modified poly(ethylene-co-vinyl acetate) (EVA-M) as pour point reducer. Commercially available EVA copolymer modified with sodium hydroxide in methanol. Partially hydrolyzed EVA was obtained and Fourier Transform InfraRed (FTIR) analysis of the modified EVA was recorded. The modified and unmodified EVA was used to crude oil of South Turgai, Kazakhstan, in order to improve the flowability of the crude oil. According to the rheological behavior of oils in the South Turgai, the findings showed that modified EVA lowered the dynamic viscosity greater compared to unmodified EVA and heat treatment. Dynamic viscosities and yield points of different oils with various temperatures with using EVA and EVA-M were studied systematically. Finally microphotograph of crystal structures two oils with using EVA and EVA-M, under same conditions, were compared and discussed.

We present a new concept for a two-pole superconducting synchronous machine. This electrical motor is composed of a classical stator yoke, and an original superconducting inductor. The inductor is composed of two coaxial circular superconducting coils separated by superconducting bulks. Both solenoids are fed by a direct current and each of them produces a magnetic field in the same direction. An inclined superconducting bulk is placed between the two solenoids. It is used as superconducting magnetic barrier. The diamagnetic behavior of a superconducting bulk cooled under zero-field is used to obtain a variation of the magnetic flux density in the air-gap. The inductor is made of low-temperature superconducting wires for the coils, NbTi, and a high-temperature superconducting YBCO bulk, cooled down to 4.2K using liquid helium for the flux barrier. The armature is wound with copper wires as a classical one. We present design and tests of this superconducting motor. We made no load, short-circuit and full load tests.